BEIRUT, Lebanon -- Hezbollah supporters have been watching the turbulence next door in Syria with apprehension. Rhetorically, the Lebanese Party of God has backed its patron in Damascus, although its embrace has grown tepid of late. But Hezbollah was worried enough to shift its weapons caches from Syria into Lebanon, reportedly, and its emissaries have been working behind the scenes to mend relations with Syria's opposition. At the core of their worry is a sectarian concern: Syria without Bashar al-Assad might be willing to jettison Hezbollah -- after all, Syria is a majority Sunni nation, and Hezbollah is a Shia standard-bearer.

"The Islamists who are fighting against Bashar Assad are not going to support us if they take power," one Hezbollah partisan told me recently in Lebanon. "They might believe in resistance against Israel, but they won't support our resistance."

If, or more likely when, Assad's government finally falls to the uprising that has shaken Syria for more than half a year, its successor will renegotiate Syria's regional relationships. Assad's long-time friends and clients have good reason to feel insecure. A more democratic Syria would represent the country's Sunni majority, which includes a fair number of Islamists. They likely won't share all the priorities of Assad's brutal minority regime, whose commitment to secular government conveniently justifies its manic clinging to absolute authority.

A Syria led in part by the Muslim Brotherhood, or by a confederation of anti-Assad forces, would probably continue to support resistance movements that fight Israel, and would likely continue relations with Iran (and, possibly, pursue warmer relations with Iraq). But it might be less vested in the ideological absolutism of the existing "Axis of Resistance," led by Hezbollah and Iran, and more interested in a new Arab nationalist front, which could unite Egypt, the Palestinians, and other post-dictatorial Arab states in an alliance that opposes Israel and some American projects from a less bellicose footing.

The threat to Hezbollah is tangible, and has broad regional implications. Assad's Syria has sponsored movements with wide followings, like Hezbollah as well as Hamas. It also has supported tiny splinter organizations known more for their roles as spoilers than as serious political players -- to name just two, The Popular Front for the Liberation of Palestine-General Command, and Palestinian Islamic Jihad. Syria has been blamed for funneling jihadis into Iraq as well as into Lebanon. And since 2005, when outrage over the murder of Lebanese Prime Minister Rafik Hariri forced Syria to withdraw its occupation forces from Lebanon, many Lebanese have seen Syrian fingerprints on a destabilizing campaign of bombings and political murders. The unmistakable threat from the Assad regime: We're willing to blow Lebanon to pieces if that's what it takes to preserve our grip on power in Damascus.

Without Syria's support, it would become exceedingly difficult for Hezbollah to funnel arms into Lebanon, especially in the event of a war. There's also a political risk. What if Syria had new rulers who continued to rail against Israel -- but attacked Hezbollah as a totalitarian or hypocritically sectarian movement? Hezbollah is vulnerable on both charges (although by no means exceptional in Lebanon). Hassan Nasrallah, the Party of God's Secretary-General, assailed Arab tyrants like Hosni Mubarak in Egypt, Muammar Qaddafi in Libya, and the royal family of Saudi Arabia. But he has remained silent about the behavior of Assad in Syria and of Iran's regimes. This double standard smacks of the same expediency of which Nasrallah has always accused Washington: supporting democracy except when it empowers groups the U.S. doesn't like.

In his most recent speech at the end of August, Nasrallah praised Syria's unremitting support for resistance and warned that the West wanted to carve Syria into pieces, reducing it to a dysfunctional pseudo-state like Lebanon. But, in a few short lines, he also said he supported reform and dialogue in Syria. "Pressure slows reform," Nasrallah said. "No one may move quickly in reform under pressure because that causes worry. ... We know that the Syrian leadership is serious in its reforms."

These lukewarm words won't woo the Syrian dissidents who have been killed by the thousands, but they reveal a movement trying to reposition itself. In a way, it's reminiscent of President Obama's rhetorical shuffling as he tried to distance himself from Mubarak in the final days of his rule in Egypt.

Syria's opposition, along with the Muslim Brothers around the region who support them, have taken note of Hezbollah's support for Assad's violent, reactionary regime. They might be willing to make a deal with Hezbollah later, but the distaste and mistrust will linger.

One Hezbollah official, Ibrahim Mousawi, told me that at root, the interests uniting the resistance axis would persist. "I don't like to make predictions based on a murky situation," he said. "But it's hard for me to imagine that a future regime in Syria would not see its interests aligned with the resistance." He has a point: Syria is stuck with the allies and leverage that is has now, unless there's some grand strategic shift in the region -- a viable plan to return the Israeli-occupied Golan Heights to Syria, or an offer from America that swings Syria out of Tehran's orbit. Neither outcome seems imminently likely.

No doubt, Iran and Hezbollah will continue to play powerful roles in the Arab world. But they're struggling to absorb a new strategic reality. Until recently, they were among the few dynamic players able to shape events, rather than react to them. Now, the stage is crowded. Turkey has emerged as a viable and savvy leader, dramatized by Prime Minister Recep Tayyip Erdogan's celebratory visit this month to Tunisia, Libya, and Egypt. Egypt itself is reawakening to its natural role as the Arab world's political center of gravity. The Palestinian leadership has energized constituents with its statehood bid. Political actors of all stripes, from labor unionists to Marxists to liberals to Islamists, are seizing the initiative and trying to steer the national and regional debate.

A genuine political contest is underway after long decades of stagnation, one that is likely to diminish the influence of Hezbollah, Syria, Iran, and perhaps even of the current Goliath, Turkey. One can see the stirrings in the response to Erdogan's Arab tour. The Muslim Brotherhood in Egypt complained about Turkish triumphalism, and has expressed annoyance at Hezbollah's claim to leadership of the resistance. The Brotherhood considers itself the dean of Islamism and anti-Israeli resistance although it has been a long time, a half a century and more, since it played the role of regional firebrand now enjoyed by Hezbollah. "Resistance existed long before us, and will continue long after we are gone," Hezbollah's Mousawi said. "We never brag that we alone are the resistance."

Humility has always been a hallmark of Hezbollah's rhetoric, but until this year the movement, along with its backers in Tehran and Damascus, enjoyed internal supremacy, and behaved like strongmen even while talking like underdogs. Now, the challenges to their power come not only from outside -- Israel, the United States, Saudi Arabia, and Arab rivals -- but from within the ranks of those who support the idea of resistance but question the bona fides of those who claim its mantle. As Syria's current regime stumbles and perhaps eventually falls, the political movements it helped give voice and comfort will seek support elsewhere.